Homogeneous hydrogenation of electron-deficient alkenes by iridium complexes
also not racemized by overnight stirring in toluene containing
10% DIPEA. Hence the very low ee obtained in toluene is not
connected with the base-induced racemization but is a property
of this reaction. Hydrogenation in methanol, of course, was
accompanied by base-induced racemization. In summary, the
nucleophilic hydrogenation could proceed enantioselectively (in
spite of a large excess of base), but here also catalyst optimization
has to be performed to obtain acceptable enantiomeric excesses.
[5] R. L. Halterman, in Comprehensive Asymmetric catalysis I, Vol. 1 (Eds:
E. N. Jacobsen, A. Pfaltz, H. Yamamoto), Springer: Berlin, 1999.
[6] A. Lightfoot, P. Schnider, A. Pfaltz, Angew. Chem., Int. Ed. 1998, 37,
2897.
[7] P. Schnider, G. Koch, R. Pretot, G. Wang, F. M. Bohnen, C. Kru¨ger,
A. Pfaltz, Chem.–Eur. J. 1997, 3, 887.
[8] J. M. Brown, in Comprehensive Asymmetric catalysis I, Vol. 1 (Eds:
E. N. Jacobsen, A. Pfaltz, H. Yamamoto), Springer: Berlin, 1999.
[9] D. G. Blackmond, A. Lightfoot, A. Pfaltz, T. Rosner, P. Schnider,
N. Zimmermann, Chirality 2000, 12, 442.
[10] K. Ka¨llstro¨m, I. Munslow, P. G. Andersson, Chem.-Eur. J. 2006, 12,
3194.
[11] R. H. Crabtree, H. Felkin, G. E. Morris, J.Organomet.Chem. 1977, 141,
205.
Conclusions
[12] L. A. Oro, D. Carmona, in HandbookofHomogeneousHydrogenation,
Vol. 1 (Eds: J. G de Vries, C. J Elsevier), Wiley-VCH: Weinhein, 2007,
p. 3.
[13] R. R. Schrock, J. A. Osborn, J. Am. Chem. Soc. 1976, 98, 2134.
[14] R. R. Schrock, J. A. Osborn, J. Am. Chem. Soc. 1976, 98, 2143.
[15] R. R Schrock, J. A. Osborn, J. Am. Chem. Soc. 1976, 98, 4450.
[16] L. A. Oro, M. Campo, D. Carmona, J. Mol. Catal. 1987, 39, 341.
[17] K. Tani, J.-i. Onouchi, T. Yamagata, Y. Kataoka, Chem.Lett. 1995, 955.
[18] A. Baeza, A. Pfaltz, Chem.-Eur. J. 2009, 15, 2266.
[19] X.-Y. Ma, K. Wang, L. Zhang, X.-J. Li, R.-X. Li, Chin. J. Chem. 2007, 25,
1503.
[20] V. Semeniuchenko, V. Khilya, U. Groth, Synlett 2009, 271.
[21] J. He, J. Zheng, J. Liu, X. She, X. Pan, Org. Lett. 2006, 8, 4637.
[22] A. K. Salakka, T. H. Jokela, K. Wa¨ha¨la¨, Beilstein. J. Org. Chem. 2006, 2,
No. 16 doi:10.1186/1860-5397-2-16.
[23] L. Li, P. Cai, Q. Guo, S. Xue, J. Org. Chem. 2008, 73, 3516.
[24] R. Meza, B. Gordillo, M. Galvan, Int. J. Quantum Chem. 2005, 104, 29.
[25] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb,
J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven, K. N. Kudin,
J. C. Burant, J. M. Millam, S. S. Iyengar, J. Tomasi, V. Barone,
B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson,
H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene,
X. Li, J. E. Knox, H. P. Hratchian, J. B. Cross, C. Adamo, J. Jaramillo,
R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi,
C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morokuma, G. A. Voth,
P. Salvador, J. J. Dannenberg, V. G. Zakrzewski, S. Dapprich,
A. D. Daniels, M. C. Strain, O. Farkas, D. K. Malick, A. D. Rabuck,
K. Raghavachari, J. B. Foresman, J. V. Ortiz, Q. Cui, A. G. Baboul,
S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A. Liashenko,
P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M. A. Al-
Laham, C. Y. Peng, A. Nanayakkara, M. Challacombe, P. M. W. Gill,
B. Johnson, W. Chen, M. W. Wong, C. Gonzalez, J. A. Pople. Gaussian
03, Revision C.02, Gaussian, Inc.: Wallingford CT, 2004.
[26] R. G. Parr, W. Yang, Density-Functional Theory of Atoms and
Molecules, Oxford University Press: Oxford, 1989.
We have found that base activation of [Ir(COD)(Phox)]-type com-
plexes switches their application to hydrogenation of electron-
deficient alkenes. The formation of nucleophilic Ir complex is
supposed, which attacks the soft electrophilic site of the substrate
and performs the hydrogenation of the corresponding double
bond. The nucleophilicity of active Ir complex is comparable to
thatofhydrazine;howeveritsstabilityissupposedtoberatherlow.
Various catalysts and substrates were tested in this reaction but a
highly efficient catalyst was not found. Nevertheless, we present
here the first example of a homogeneous hydrogenation of 7-
methoxyisoflavone and related electron-deficient compounds,
which otherwise fail to enter similar reactions, catalyzed by known
widely used complexes of Rh, Ir and Ru. This reaction allows hy-
drogenation of sufficiently electrophilic substrates (with low-lying
LUMO) with sterically unhindered C C bond.
Acknowledgments
SV thanks the Herbert-Quandt foundation and the German
Academic Exchange Service (DAAD) for doctoral fellowships. S.V.
again thanks the partnership program between the University of
Konstanz and the NTSU Kiev for the opportunity to perform his
doctoral studies in Konstanz. We are grateful to Anke Friemel,
Ulrich Haunz, Dr Reinhold Weber, Dr Sascha Keller and Dr Dmitry
Galetskiy (Konstanz University) for measurement of NMR and mass
spectra and to Dr Thomas Huhn for help with preparing the
manuscript. We are grateful to Umicore, MCAT, Bayer AG, Merck
KGaA, Wacker AG, Dr Ya. L. Garazd, Dr M. M. Garazd and Dr V. S.
Moskvina for generous gifts of reagents.
[27] C. J. Cramer, Essentials of Computational Chemistry, Wiley:
Chichester, 2004.
Supporting information
[28] E. R. Davidson, S. Chakravorty, Theor. Chim. Acta 1992, 83, 319.
[29] P. Maib, Z. Jerzmanowska, Pol. J. Chem. 1987, 61, 111.
[30] J. Staunton, in Comprehensive Organic Chemistry: The Synthesis and
Reactions of Organic Compounds, Vol. 4. Heterocyclic Compounds
(Ed.: P. G Sammes), Pergamon Press: Oxford, 1979, p. xiii.
[31] F. Castaneda, G. B. Marini-Bettolo, Rendiconti Istituto Superiore di
Sanita (Italian Edition) 1964, 27, 94; Chem. Abstr. 1965, 62, 8924.
[32] V. Chiodoni, Chimica e l’Industria (Milan, Italy) 1963, 45, 968; Chem.
Abstr. 1964, 60, 60622.
[33] F. C. Magliona, G. B Marini-Bettolo, Gazz. Chim. Ital. 1963, 93, 345.
[34] G. B Marini-Bettolo, C. G. Casinovi, I. L d’Alburquerque, Gazz. Chim.
Ital. 1964, 94, 366.
[35] P. Papini, S. Checchi, M. Ridi, Gazz. Chim. Ital. 1954, 84, 769.
[36] T. Iwai, T. Fujihara, Y. Tsuji, Chem. Commun. 2008, 6215.
[37] C. Metallinos, J. Zaifman, L. Van Belle, L. Dodge, M. Pilkington,
Organometallics 2009, 28, 4534.
Supporting information may be found in the online version of this
article.
References
[1] J. G. de Vries, C. J. Elsevier, Handbook of Homogeneous
Hydrogenation, Wiley-VCH: Weinheim, 2007.
[2] E. N. Jacobsen, A. Pfaltz, H. Yamamoto, Comprehensive Asymmetric
Catalysis, Springer: Berlin, 1999, (Supplement, Springer, Berlin,
2004).
[3] H. U. Blaser, E. Schmidt, Asymmetric Catalysis on Industrial Scale:
Challenges, Approaches and Solutions, Wiley-VCH: Weinheim, 2004.
[4] R. H. Crabtree, in The Handbook of Homogeneous Hydrogenation,
Vol. 1 (Eds: J. G. De Vries, C. J. Elsevier), Wiley-VCH: Weinhein, 2007.
c
Appl. Organometal. Chem. 2011, 25, 804–809
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